It is known to provide the side doors of automotive vehicles for the transport of people with stiffening structures such as beams or girders which are capable of resisting a collision from the side and thus lateral collapse of the door or the vehicle.
Such structural shapes have included tubes, I-beams and like stiffening members and have the purpose of so stiffening the thin sheet metal side walls, especially at a level of the greatest possibility of impact, i.e. bumper height, that the door will not be pressed into the vehicle to the point that the passengers seated therein can suffer injury.
To minimize the weight of the vehicle, such girders have been fabricated from light metal, e.g. magnesium, aluminum, aluminum-magnesium alloys.